Dental radiology equipment as described in French patent No. 547,495 and European patent No. 0,129,451 is known.
Such equipment comprises an x-ray source that emits radiation directed to a tooth located in a patient's mouth and behind which is an intraoral sensor that receives the x-rays that have passed through the tooth.
This sensor comprises:                a scintillator on entry to convert the x-rays that have passed through the tooth into visible radiation,        a fiber optic plate to transmit the converted visible light to a charge-coupled device (CCD) type detector, which reconverts the converted visible light into an analog electrical signal, while absorbing the residual x-rays that have not been converted into visible light.        
The electrical signal is amplified and transmitted in analog form through a long cable, to a remote processing and display workstation where the signal is digitized and processed to produce an mage that is then viewed on a display screen.
Also known, according to U.S. Pat. No. 5,912,942, is a type of x-ray detector wherein an active pixel sensor (APS) uses CMOS manufacturing technology.
In the above-mentioned patent, the radiology equipment described therein comprises:                a source of x-rays passing through an object,        a scintillator that converts the x-rays that have passed through the object into visible light,        possibly, a fiber optic plate transmitting the converted visible light to an active pixels array (detector) that converts it into an analog electrical signal.        
In this patent, it is explained that the signal can be converted into a digital signal in the sensor itself or in an interface case separate from the sensor and remote from the image signal processing and display unit.
In the dental radiological equipment that has just been described, it is not known whether the x-ray dose used to pass through a patient's tooth is sufficient to produce a good quality image on the display screen (correct exposure level), whether the dose is insufficient (under-exposure) or even excessive (over-exposure).
In some cases, a particularly experienced user can, by examining the screen image of the tooth, assess whether the patient has been exposed to too high a dose of x-rays and thus adjust the equipment for future image taking.
However, this is not something most users can do, as they do not always know how to analyze the tooth image reliably.